Ground level three phase electrical power distribution transformer installations need to be protected against changing weather conditions as well as against acts of vandalism. For this reason, various housings and protective equipments have been used over the years. One of the desired characteristics of the housing employed is that it must restrict the access to the transformer and its related components only to authorized operating and maintenance personnel, without obstructing in any way the work that these personnel need to do. Various types of transformer housings have been reported in the patent literature.
For instance, U.S. Pat. No. 3,014,158 discloses a ground level transformer adapted primarily for use in conjunction with underground distribution systems, which is self-contained, not requiring either a separate enclosure or separate protective equipment for its installation, having all its live parts enclosed in a locked tamper-proof housing. The transformer housing contains two compartments, one of which contains oil, a transformer and its associated circuitry, as well as a switch and a fuse. The other compartment contains high and low voltage bushings which are electrically connected with the transformer, as well as manually operable means to connect or disconnect from the transformer circuitry the switch located inside the oil-containing compartment, as well as to remove or insert the fuse elements into the latter compartment.
U.S. Pat. No. 3,335,380 discloses a ground level transformer with cabinet. The invention relates particularly to housings for a three phase, ground level distribution transformer and associated switching and protective equipment, which can be shipped in knocked-down condition and is modular in construction. The invention provides also a cabinet for the switching and protective equipment which is unitary with the transformer casing and can be expanded to the left or to the right of the transformer casing to the extent desired. The cabinet is tamper-proof and weatherproof, and allows an unobstructed access to the equipment for the easy mounting of fuses, switches, lightning arresters, meters and potheads at any desired location within the cabinet.
U.S. Pat. No. 3,376,086 discloses a tamper-proof and weatherproof housing for enclosing an electrical apparatus at ground level, which allows simultaneous access to the apparatus from three sides and from the top of the housing. An adequate ventilation system for the electrical apparatus enclosed by the housing is also provided.
U.S. Pat. No. 3,870,932 discloses a terminal compartment cover means for pad-mounted transformers of the type having a tank integral with high and low voltage terminating compartments. The high voltage and low voltage segments of the compartment are enclosed by separated cover means, in a manner which permits isolation of the high voltage segment when the low voltage segment is opened. Each cover is of an inverted L-shaped cross section when closed, hinged along its upper edge to the tank and padlocked at its lower edge. The high voltage segment cover has a barrier facing the low voltage side which prevents access to the high voltage terminals. Inter-fitting water drainage channel means are provided on the two covers.
U.S. Pat. No. 4,556,758 discloses a pad-mounted transformer having an improved terminal cover-to-tank interface, which is formed by two equal, opposite facing acute angles in the cover, and a single obtuse angle in the adjacent tank. Closure of the terminal cover causes a leg of the obtuse angle to enter the vertex of an acute angle, which creates a tortuous path for elongated foreign objects, such as a wire, providing also a sloping surface which causes pry-bars to slide out of the interface seam. The cover-to-tank interface requires no welding, it forms no blind spots which resist application of paint, and it forms no moisture traps, thus greatly improving the corrosion resistance of the pad-mounted transformer. The tamper-resistance of the tank-terminal cover interface is also enhanced, as it creates a tortuous path for a wire, causing it to be sharply bent, and then directed into a box-like enclosure, against a harmless flat portion of the tank wall.
U.S. Pat. No. 5,189,257 discloses a transformer having an integral cabinet with an apparatus for hinging and clamping the cover of the cabinet onto its base. The hinge is formed by an L-shaped member extending from a lip surrounding a planar top formed in the cover. A flange having rearward and downward extending portions extends from the rear wall of the cabinet base. The hinge engages a slot formed in the downward extending portion of the flange. The distance from the hinge to the cover top is less than the distance from the slot to the upper edge of the rear wall on which the cover top rests. Thus, rotation of the cover into the closed position with the hinge engaged causes elastic deformation of the hinge, thereby creating a spring force which clamps the cover onto the base. Elastic deformation in the flange imparts additional clamping force. Sufficient clearance is provided for this elastic deformation by either sloping the rearward extending portion of the flange or sloping the planar top of the cover.
U.S. Pat. No. 5,527,988 discloses a tank for an oil-filled pad-mounted electrical distribution transformer. The tank includes a front plate and a side panel unit connected to the front plate. The side panel unit is formed of a bent sheet of metal. Two of the side panels form obtuse included angles with adjoining side panels. A floor plate of the tank is sized to fit inside of the side panel unit so as to be capable of being secured at any desired elevation. The floor plate includes reinforcing channels.
U.S. Pat. No. 6,114,624 discloses a pad-mounted distribution transformer tank, wherein hem-bend flanges are constructed upper edge of the front terminal panel to act as a heat shield to protect the painted surface during the welding operation on the cover. Hem-bend flanges are also utilized on the sidewalls of the tank to improve the structural strength of the tank flange.
U.S. Pat. No. 6,422,612 discloses a door latch mechanism for pad-mounted transformer cabinet, in the form of a shaped plate including rod apertures at opposing ends for connecting with the latch rods and a door handle aperture intermediate the rod apertures for fastening to the cabinet operating door handle. A door stop in the form of a U-shaped rod is positioned on the bottom of the cabinet door frame to hold the cabinet door in the open position until and unless one end is released from the door bottom.
Lastly, U.S. Pat. No. 2003/0102141 Pat. Application discloses an improved pad-mount transformer enclosure for a 3-phase pad-mount distribution transformer or the like, having a wiring compartment utilizing multiple hinge points on each side panel with an additional set of hinges located at the back of the compartment area to allow the doors to be opened as normal or to allow the sides to be also opened, allowing the wiring compartment to be totally exposed on all three sides. The tank of the transformer enclosure may have a cover secured in a manner that allows the cover to be removed with simple hand tools while preventing unauthorized removal thereof, that increases tank top structural rigidity, and that does not trap water on the tank cover.
Despite of all the improvements that have been done over the past years to the ground level transformers, as well as to their related components, a system which is modular and which is coupled to a self-assembly cabinet has not been reported in the related art. Thus, it is an object of the present invention to propose a functional improved system comprising a modular tank coupled to a self-assembly cabinet for ground level transformers. The characteristic design of such a system allows attaining substantial economical savings due to reduced oil consumption, as well as due to a smaller requirement of materials for the construction of the tank and associated reduced assembly times, when compared with conventional tank configurations.
It is a further object of the present invention to provide a modular tank coupled to a self-assembly cabinet for ground level transformers whose materials and fabrication costs are reduced in at least 5% compared to conventional cabinet configurations.
It is a further object of the present invention to provide a modular tank coupled to a self-assembly cabinet for ground level transformers whose improved design allows achieving a substantial reduction in the total number of parts needed for its assemblage, from the 250 pieces used in conventional cabinet configurations to 74 pieces used in the new design.
It is a further object of the present invention to provide a modular tank coupled to a self-assembly cabinet for ground level transformers whose constituting parts are automatically fixed to each other during the cabinet assembly, so that the only pieces that need additional fixation means are the door locks.
It is a further object of the present invention to provide a modular tank coupled to a self-assembly cabinet for ground level transformers whose assembly requires using a reduced number of different parts compared to conventional cabinet configurations.
It is a further object of the present invention to provide a modular tank coupled to a self-assembly cabinet for ground level transformers whose constituting parts can be readily made in existing machine shops.
It is a further object of the present invention to provide a modular tank coupled to a self-assembly cabinet for ground level transformers which can be manually assembled.
This and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.